This section is from the book "Nature's Garden", by Neltje Blanchan. Also available from Amazon: Nature's Garden; An Aid To Knowledge Of Our Wild Flowers And Their Insect Visitors.
Flower-head - Composite of tubular florets only, intense reddish-purple thistle-like heads, borne on short, branched peduncles and forming broad, flat clusters; bracts of involucre, brownish purple, tipped with awl-shaped bristles. Stem: 3 to 9 ft. high, rough or hairy, branched. Leaves: Alternate, narrowly oblong or lanceolate, saw-edged, 3 to 10 in. long, rough.
Flowering Season - July - September.
Distribution - Massachusetts to Georgia, and westward to the Mississippi.
Iron-Weed Or Flat Top (Vernonia Noveboracensts.)
Emerson says a weed is a plant whose virtues we have not yet discovered; but surely it is no small virtue in the iron-weed to brighten the roadsides and low meadows throughout the summer with bright clusters of bloom. When it is on the wane, the asters, for which it is sometimes mistaken, begin to appear, but an instant's comparison shows the difference between the two flowers. After noting the yellow disk in the centre of an aster, it is not likely the iron-weed's thistle-like head of ray florets only will ever again be confused with it. Another rank-growing neighbor with which it has been confounded by the novice is the Joe Pye weed, a far paler, pinkish flower, as one who does not meet them both afield may see on comparing the colored plates in this book.
To each tiny floret, secreting nectar in its tube, many insects, attracted by the bright color of the iron-weed standing high above surrounding vegetation, come to feast. Long-lipped bees and flies rest awhile for refreshment, but butterflies of many beautiful kinds are by far the most abundant visitors. Pollen carried out by the long, hairy styles as they extend to maturity must attach itself to their tongues. The tiger swallow-tail butterfly appears to have a special preference for this flower. (See p. 46.)